Nanoparticles in nuclear medicine: From diagnostics to therapeutics

The use of nanoparticles in nuclear medicine is paradoxical. While several nanoformulations, such as 99mTc colloids, have been used for diagnosis for decades, only a few new radionanomedicines have been able to reach the market, despite extensive preclinical efforts. This contradiction is dictated by the unique features of nanoparticles, such as (potential) prolonged circulation times, slow compartment exchanges, and large accumulations in the mononuclear phagocyte system, which allow for certain specific applications while preventing others. In this review, we discuss the development and clinical application of radiolabeled nanoparticles as imaging agents for disease diagnosis and patient stratification, as well as their promise and potential to be used as next-generation formulations to improve the efficacy of radiotherapy.